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<div class="titlepage"><div><div><h3 class="title">
<a name="math_toolkit.high_precision.use_mpfr"></a><a class="link" href="use_mpfr.html" title="Using With MPFR or GMP - High-Precision Floating-Point Library">Using With MPFR
      or GMP - High-Precision Floating-Point Library</a>
</h3></div></div></div>
<p>
        The special functions and tools in this library can be used with <a href="http://www.mpfr.org" target="_top">MPFR</a>
        (an arbitrary precision number type based on the <a href="http://gmplib.org/" target="_top">GNU
        Multiple Precision Arithmetic Library</a>), either via the bindings in
        <a href="../../../../../../boost/math/bindings/mpfr.hpp" target="_top">boost/math/bindings/mpfr.hpp</a>,
        or via <a href="../../../../../../boost/math/bindings/mpfr.hpp" target="_top">boost/math/bindings/mpreal.hpp</a>.
      </p>
<p>
        <span class="bold"><strong>New projects are recommended to use <a href="../../../../../../libs/multiprecision/doc/html/index.html" target="_top">Boost.Multiprecision</a>
        with GMP/MPFR backend instead.</strong></span>
      </p>
<p>
        In order to use these bindings you will need to have installed <a href="http://www.mpfr.org" target="_top">MPFR</a>
        plus its dependency the <a href="http://gmplib.org" target="_top">GMP library</a>.
        You will also need one of the two supported C++ wrappers for MPFR: <a href="http://math.berkeley.edu/~wilken/code/gmpfrxx/" target="_top">gmpfrxx (or mpfr_class)</a>,
        or <a href="http://www.holoborodko.com/pavel/mpfr/" target="_top">mpfr-C++ (mpreal)</a>.
      </p>
<p>
        Unfortunately neither <code class="computeroutput"><span class="identifier">mpfr_class</span></code>
        nor <code class="computeroutput"><span class="identifier">mpreal</span></code> quite satisfy
        our conceptual requirements, so there is a very thin set of additional interfaces
        and some helper traits defined in <a href="../../../../../../boost/math/bindings/mpfr.hpp" target="_top">boost/math/bindings/mpfr.hpp</a>
        and <a href="../../../../../../boost/math/bindings/mpreal.hpp" target="_top">boost/math/bindings/mpreal.hpp</a>
        that you should use in place of including 'gmpfrxx.h' or 'mpreal.h' directly.
        The classes <code class="computeroutput"><span class="identifier">mpfr_class</span></code> or
        <code class="computeroutput"><span class="identifier">mpreal</span></code> are then usable unchanged
        once this header is included, so for example <code class="computeroutput"><span class="identifier">mpfr_class</span></code>'s
        performance-enhancing expression templates are preserved and fully supported
        by this library:
      </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">bindings</span><span class="special">/</span><span class="identifier">mpfr</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">special_functions</span><span class="special">/</span><span class="identifier">gamma</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
<span class="special">{</span>
   <span class="identifier">mpfr_class</span><span class="special">::</span><span class="identifier">set_dprec</span><span class="special">(</span><span class="number">500</span><span class="special">);</span> <span class="comment">// 500 bit precision</span>
   <span class="comment">//</span>
   <span class="comment">// Note that the argument to tgamma is</span>
   <span class="comment">// an expression template - that's just fine here.</span>
   <span class="comment">//</span>
   <span class="identifier">mpfr_class</span> <span class="identifier">v</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span><span class="special">::</span><span class="identifier">tgamma</span><span class="special">(</span><span class="identifier">sqrt</span><span class="special">(</span><span class="identifier">mpfr_class</span><span class="special">(</span><span class="number">2</span><span class="special">)));</span>
   <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">setprecision</span><span class="special">(</span><span class="number">50</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">v</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
        Alternatively use with <code class="computeroutput"><span class="identifier">mpreal</span></code>
        would look like:
      </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">bindings</span><span class="special">/</span><span class="identifier">mpreal</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">special_functions</span><span class="special">/</span><span class="identifier">gamma</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
<span class="special">{</span>
   <span class="identifier">mpfr</span><span class="special">::</span><span class="identifier">mpreal</span><span class="special">::</span><span class="identifier">set_precision</span><span class="special">(</span><span class="number">500</span><span class="special">);</span> <span class="comment">// 500 bit precision</span>
   <span class="identifier">mpfr</span><span class="special">::</span><span class="identifier">mpreal</span> <span class="identifier">v</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span><span class="special">::</span><span class="identifier">tgamma</span><span class="special">(</span><span class="identifier">sqrt</span><span class="special">(</span><span class="identifier">mpfr</span><span class="special">::</span><span class="identifier">mpreal</span><span class="special">(</span><span class="number">2</span><span class="special">)));</span>
   <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">setprecision</span><span class="special">(</span><span class="number">50</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">v</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
        There is a concept checking test program for mpfr support <a href="../../../../../../libs/math/test/mpfr_concept_check.cpp" target="_top">here</a>
        and <a href="../../../../../../libs/math/test/mpreal_concept_check.cpp" target="_top">here</a>.
      </p>
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